Electronic Accelerator Function - GF30.20-P-3015MRS

Engine 264.9 in model 205, 253 

Function requirements, general

• Engine runs

The ME-SFI [ME] control unit (N3/10) detects the engine running via the evaluation of the crankshaft Hall sensor signals (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

Electronic accelerator, general points 

The electronic accelerator function is integrated in the ME-SFI [ME] control unit and controls, depending on the driver input and operating conditions, the opening angle of the throttle valve. The ME-SFI [ME] control unit regulates the throttle valve position, dependent on the following signals:

• Engine load

  Pressure and temperature sensor downstream of throttle valve (B28/27)

• Accelerator pedal position

  The powertrain control unit (N127) reads in the accelerator pedal sensor (B37) signals directly, and transmits the accelerator pedal position via the drive CAN (CAN C1) to the ME-SFI [ME] control unit.

• Brake actuation and cruise control requests

  The Electronic Stability Program control unit (N30/4) transmits the signals via the suspension FlexRay (Flex E), the powertrain control unit, and the drive CAN to the ME-SFI [ME] control unit.

• Drive position

  The fully integrated transmission control unit (Y3/8n4) sends the signal via the drive CAN to the ME-SFI control unit.

• Engine torque request (with code 239 (Active Distance Assist DISTRONIC) or with code 23P (Driving Assistance Package))

  Code 239 (Active Distance Assist DISTRONIC) 

  The Distance Pilot DISTRONIC controller unit (A108/1) (model 205) or the Active Distance Assist DISTRONIC electric controller unit (A108/1) (model 253) transmits the engine torque request via the suspension FlexRay, powertrain control unit, and drive CAN to the ME-SFI [ME] control unit.

  Code 23P (Driver Assistance Package) 

  The Mercedes-Benz Intelligent Drive control unit (N62/4) transmits the engine torque request via the suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.

  The requirements of the torque coordination function are also taken into account.

  The electronic accelerator function is subdivided into the following points:

  • Engine torque control 
  • Driveability functions and load change damping 
  • Reverse travel 
  • Adaptive accelerator pedal 

  Engine torque control 

  The ME-SFI [ME] control unit regulates the engine torque by:

  • Adjusting the opening angle of the throttle valve
  • Extending or shortening the fuel injection duration
  • Advancing or retarding the ignition angle. In this way, very rapid change of the engine torque is possible.

  The ME-SFI [ME] control unit actuates the following components for this purpose:

  • Throttle valve actuator (M16/6)
    • Throttle valve actuator motor (M16/6m1)
  • Ignition system
    • Cylinder 1 ignition coil (T1/1)
    • Cylinder 2 ignition coil (T1/2)
    • Cylinder 3 ignition coil (T1/3)
    • Cylinder 4 ignition coil (T1/4)
  • Fuel injection system
    • Cylinder 1 fuel injector (Y76/1)
    • Cylinder 2 fuel injector (Y76/2)
    • Cylinder 3 fuel injector (Y76/3)
    • Cylinder 4 fuel injector (Y76/4)

    The engine torque is solely determined by the accelerator pedal input, if no engine torque requests (e.g. cruise control request) are active. The ME-SFI [ME] control unit detects the throttle valve position via the following components:

    • Actual value potentiometer 1 (M16/6r1)
    • Actual value potentiometer 2 (M16/6r2),

    Driveability functions and load change damping 

    Rapid accelerator pedal movements are not immediately translated into an engine torque. The engine torque is adapted to the request in a dampened manner. This avoids jolting in the drivetrain and improves ride comfort.

    For this purpose, the throttle flap is only closed to the idle speed range in a delayed manner in the case of a sudden release of the accelerator. In this way, the engine torque reduces slowly and the vehicle does not slow down with jerks.

    The drivability functions and the throttle change damping take place on the basis of the following signals:

    • Accelerator pedal actuation (rapid, slow)
    • Engine speed

      Crankshaft Hall sensor

    • Coolant temperature

      Coolant temperature sensor (B11/4)

    • Throttle valve position

      Actual value potentiometer 1

      Actual value potentiometer 2

    • Wheel speed

      The Electronic Stability Program control unit transmits the signals via the suspension FlexRay, the powertrain control unit, and the drive CAN to the ME-SFI [ME] control unit.

    Reverse travel 

    During reversing, the throttle valve is opened more slowly and engine torque is limited to approx. 50 %. This optimizes ride comfort and driving safety in reverse travel.

    Adaptive accelerator pedal 

    The ME-SFI [ME] control unit changes the response time of the electronic accelerator pedal depending on the vehicle speed calculated from the wheel speeds. At higher vehicle speeds, a slightly steeper accelerator pedal curve is used in order to improve the response time (reduction of free travel).

    Further functions which support the electronic accelerator, are:

    • Engine speed control
    • Torque coordination
    • Engine limp-home mode